The present invention relates to compressors, and more specifically to bearings for rotatably supporting the crankshaft of the compressor.
In a typical hermetic compressor assembly, a motor and a compression mechanism are mounted in the compressor housing and drivingly linked by a crankshaft or drive shaft. Often, the compression mechanism is supported by a frame or crankcase through which the drive shaft extends to drivingly engage the compression mechanism. An eccentric portion is typically provided on the drive shaft and engages the compression mechanism. In a rotary compressor, a roller is conventionally mounted on the eccentric portion with a journal bearing located between the roller and the eccentric portion of the drive shaft. The drive shaft is also typically rotatably supported in the crankcase or bearing support by a main bearing at a location between the roller and motor driving the crankshaft and at an end of the crankshaft opposite the motor by an outboard bearing located on the opposite side of the compression mechanism from the main bearing.
Oftentimes an opening or aperture in the crankcase that faces the compressor mechanism has dimensions which are governed by the functionality of the compressor mechanism. For example, in a rotary compressor, the opening in the crankcase facing the roller of the compressor mechanism must be sufficiently small so that the opening does not intrude into the compression chamber and allow the release of vapors from the compression chamber. This, in turn, can influences the dimensions of the crankshaft by defining a maximum diameter of at least that length of the crankshaft which is inserted through the crankcase opening. The bearings mounted on this length of the crankshaft is also thereby affected.
The present invention relates to compressor assemblies and provides a sleeve on the crankshaft of the compressor assembly and a bearing mounted on the sleeve to rotatably support the crankshaft. As described below, this facilitates the use of a bearing on a length of the crankshaft that has been inserted through an opening in the crankcase wherein the bearing has an inside diameter which is at least as great as the opening in the crankcase by mounting the bearing on the sleeve.
The present invention comprises, in one form thereof, a compressor assembly that includes a compressor mechanism, a motor having a stator and a rotor and a crankcase (56, 72) disposed between the compressor mechanism and the rotor wherein the crankcase defines a first aperture (92) having a first minimum diameter D1. A bearing support (57, 73) defining a second aperture (95) having a second minimum diameter D2 is also provided and the second aperture is disposed between the crankcase aperture and the rotor. A crankshaft (44, 46), extending from a first end (61, 75) to an opposite second end (60, 76), is operably coupled to the rotor proximate the first end (61, 75) and operably coupled to the compressor mechanism proximate the second end (60, 76). The crankshaft (44, 46) extends through the first and second apertures and a length (80) of the crankshaft extending within the first aperture and to the first end (61, 75) has an outer diameter D3 no greater than the first minimum diameter. At least a portion (82) of the crankshaft between the first aperture and the second end defines an outer diameter D4 greater than the first minimum diameter. A sleeve (98) is mounted on the crankshaft and is at least partially disposed within the second aperture. The sleeve defines an outer diameter D5 at least as great as the first minimum diameter and a bearing (86) is disposed within the second aperture and engaged with the sleeve whereby the bearing provides rotational support for the crankshaft.
A second bearing support and a second bearing mounted within the second bearing support may also be provided in some embodiments wherein the second bearing rotatably supports the crankshaft at a position on the crankshaft between the first aperture and the second end where the crankshaft defines an outer diameter greater than the first minimum diameter.
The crankshaft may include an eccentric portion between the first aperture and the second end defining an outer diameter greater than said first minimum diameter wherein the eccentric portion is operably coupled with the compressor mechanism. The crankcase may also include a planar surface surrounding the first aperture wherein the eccentric portion has a roller mounted thereon wherein the roller extends radially outwardly of the first aperture through a complete rotation of the crankshaft. The compressor mechanism may also be a rotary compressor and include a roller mounted on the eccentric portion with a third bearing operably disposed between the eccentric portion and the roller.
The sleeve of particular embodiments may define an outer diameter that is greater than said first minimum diameter. The sleeve may also have a substantially cylindrical radially inward surface engaging the crankshaft and a substantially cylindrical radially outward surface engaging the bearing. The bearing may be a roller bearing having an inner raceway engaged with the sleeve, an outer raceway engaged with the bearing support and a set of substantially cylindrical rollers disposed between said inner and outer raceways. The bearing support may be integrally formed with the crankcase.
The invention comprises, in another form thereof, a compressor assembly including a compressor mechanism, a motor having a stator and a rotor and a bearing support member (57, 73) disposed between the compressor mechanism and the rotor. The bearing support member defines a stepped opening having a first portion (92) defining a first minimum diameter D1 and a second portion (95) defining a second minimum diameter D2. The second portion is disposed between the rotor and the first portion and the second minimum diameter is greater than the first minimum diameter. A crankshaft (44, 46), extending from a first end (61, 75) to an opposite second end (60, 76), is operably coupled to the rotor proximate the first end and operably coupled to the compressor mechanism proximate the second end. The drive shaft extends through the first and second portions of the opening wherein a length (80) of the crankshaft extending within the opening and to the first end has an outer diameter D3 no greater than the first minimum diameter and wherein at least a portion (82) of the crankshaft between the opening and the second end defines an outer diameter D4 greater than the first minimum diameter. A sleeve (98) is mounted on the crankshaft and at least partially disposed within the second portion of the opening. The sleeve defines an outer diameter D5 at least as great as the first minimum diameter and a bearing (86) is disposed within the second portion of the opening and engaged with the sleeve whereby the bearing provides rotational support for the crankshaft.
The crankshaft may also include an eccentric portion between the first portion of the stepped opening and the second end that defines an outer diameter greater than the first minimum diameter wherein the eccentric portion is operably coupled with the compressor mechanism.
The invention comprises, in yet another form thereof, a method of manufacturing a compressor assembly that includes providing a crankcase (56, 72) defining a first aperture (92) having a first minimum diameter D1 and a crankshaft (44, 46) having a first end (61, 75) and an opposite second end (60, 76). The method also includes inserting the first end of the crankshaft through the first aperture wherein the crankshaft extends through the first aperture and at least a portion (82) of the crankshaft between the first aperture and the second end defines an outer diameter D4 greater than the first minimum diameter. A sleeve (98) is mounted on the crankshaft after inserting the first end of the crankshaft through the first aperture at a location between (80) the first end and the first aperture wherein the sleeve includes an outer diameter D5 at least as great as the first minimum diameter. The method also includes mounting a bearing (86) on the sleeve for rotatably supporting the crankshaft and operably coupling a compressor mechanism to the crankshaft.
The portion of the crankshaft between the first aperture and the second end defining an outer diameter greater than the first minimum diameter in some embodiments may be an eccentric portion and the compressor mechanism may be operably coupled to the eccentric portion. The method may also include operably coupling a motor to the crankshaft between the first end and the first aperture. The bearing may include an inner raceway, an outer raceway and a set of substantially cylindrical rollers disposed between the inner and outer raceways and the mounting of the bearing on the sleeve may comprise engaging a radially inward facing surface on said inner raceway with the sleeve.
The method may also include providing a bearing support defining a second aperture having a second minimum diameter greater than the first minimum diameter and disposing the bearing within the second aperture. The crankcase may, in some embodiments, include an integral bearing support portion defining a second aperture having a second minimum diameter greater than the first minimum diameter wherein the method further includes disposing the bearing within the second aperture.
One advantage of the present invention is that the use of a sleeve with the bearing positioned between the crankcase aperture and the motor allows the bearing to have a larger inside diameter than the minimum diameter of the crankcase aperture thereby providing greater support for the crankshaft.
A further advantage of the present invention is that sleeve can have a thickness which allows the bearing positioned thereon to be a standard sized bearing rather than a custom sized bearing whereby the compressor assembly can be manufactured in a cost efficient manner.